The overall objective of this proposed research is the study of: 1) the immunopathology of EAS, i.e., the extent of contribution of the major classes of humoral antibodies and thymus derived vs. bone marrow derived subclasses of lymphocytes for lesion induction; 2) the efficacy of various specific immunosuppressive treatments in inhibiting either the induction or development of such lesions; and 3) the possible contribution of the major classes of humoral antibody in the inhibition of induction of the lesion. Passive and adoptive transfer and reconstitution experiments will be used to elucidate the components of the immune system required for the production of EAS. Various specific immunosuppressive treatments (including administration of immunogen or specific antisera) will be utilized to assay for inhibition of EAS induction as determined histopathologically. The role of IgG and IgM antibody in inhibiting the induction of EAS will be evaluated by passive transfer studies. These experiments will be pursued as indiciate by accumulating results along lines leading to a more complete understanding of the mechanisms involved in cell mediated immunity and the means by which antibody regulates these processes. Such information may also be useful clinically in the treatment of autoimmune disease, graft-rejection, and cancer therapy.